Why Car Engines Don't Need Back Pressure + Exhaust Scavenging Do cars need back pressure? How should you size an exhaust? What exhaust diameter is too large, or too small? What is exhaust scavenging?

If you belong to the camp of people who still believe that back pressure helps your Harley-Davidson, or any engine, for that matter, we hate to break it to you, but you're wrong. Ask any engineer, ...